Heat generation from swirl-stabilized aluminum-air flames

• An aluminum-air flame was swirl-stabilized. • The overall power dissipated by the flame ranged from 5 to 25 kW. • About 45% of the produced heat was recovered in the combustion chamber. • The overall conversion efficiency of Al into Al 2 O 3 ranged from 68 to 100%. • XRD analysis on collected samples reveals numerous crystallographic structures of Al 2 O 3. To limit global warming, new ways of transporting and storing energy are required. In such a context, metals are currently being considered as suitable energy carriers. In this investigation, aluminum-air flames were stabilized by a swirled-flow in a combustion chamber for heat production. Commercial Al particles were tested in various size range (from 0 to 400 µm). The total air flow rate injected varied from 5.6 (n)m 3 /h to 8 (n)m 3 /h corresponding to geometric swirl number ranging from 0.7 to 28. Self-igniting and continuous aluminum flames stopped after more than five minutes were established. Aluminum particles in the size range 0 to 36 µm were needed to ignite the flame. Indeed, no flame ignition was obtained with the 36 to 50 µm size range under these conditions. Increasing the swirl number from 7 to 14 and 28 enabled increasing the overall Al conversion rate. More than 45 % of the heat delivered by aluminum combustion was recovered in the combustion chamber which was water-cooled. Samples collected in the combustion chamber were observed by optical microscopy. Some unburnt or partly burnt aluminum particles were observed mainly for the samples collected at the inlet of the combustion chamber.